1. Field of the Invention
The present invention relates generally to heating pads and, more specifically, to a device for melting snow and ice accumulating on a rooftop surface and collecting the resulting liquid for removal from the surface of the roof.
2. Description of the Prior Art
Numerous devices for heating a surface have been provided in the prior art. For example, U.S. Pat. Nos. 2,617,005; 2,844,696; 3,806,702; 4,247,756; 4,794,228; 4,967,057 and 5,380,988 Japanese Patent No. 188,069 all are illustrative of such prior art. Thus, while these units may be suitable for the particular purpose to which they address, they would not be as suitable for the purposes of the present invention as heretofore described.
U.S. Pat. No. 2,617,005 relates to a warming device and it is primarily an object of the invention to provide a warming device adapted for use by animals. The device is in the nature of a bed including electrical heating means having a normally open operating circuit together with means whereby the weight of the animal occupying the device effects the closing of the circuit.
U.S. Pat. No. 2,844,696 relates to heating devices and more particularly to a snow melting mat. This device is for use on steps, entrances to buildings, on walks or the like so as to remove snow and ice therefrom by melting and thereby reducing the possibility of accidents occurring.
U.S. Pat. No. 3,806,702 discloses a weatherproof electrically insulative mat having an electrical heat producing conductor therein and adapted for placement on an exterior surface to prevent accumulation of snow on such surface. A control system for supplying current to the conductor including a precipitation sensor, a temperature sensor and a control unit responsive to the sensors so that power is supplied to the conductor in the mat only when there is precipitation and the temperature is below 35.degree.. An improved mat structure that is approximately symmetrical of the central plane thereof so that when one side of the mat wears the mat can be reversed.
U.S. Pat. No. 4,247,756 discloses a heated rubber mat comprising upper and lower rubber panels and an intervening carbon-loaded electrically resistive rubber heating element. All are vulcanized together to form a unitary mat structure characterized by good flexibility permitting rolling up the mat in any direction and by permanent shape retention, said heating element having spaced, flexible electrodes fully enclosed therein and bonded thereto, along with associated, thermostatically controlled current receiving means, whereby current may be transmitted through the portions of the heating element lying between said electrodes to generate heat and whereby the mat may be maintained at the desired temperature.
U.S. Pat. No. 4,967,057 discloses individual electrically heated mats, self-regulated by use of an electrical element whose resistance varies proportionately with its temperature, used for covering walking areas to prevent accumulation of snow and ice. Each mat is provided with male and female electrical connections on the ends of short power cords to permit any number of mats to be chained together in electrical parallel and to be used to cover, for example, a flight of stairs by positioning one mat on each stair.
U.S. Pat. No. 5,380,988 discloses a heated mat structure provides a plurality of thin heated mats, each releasably interconnected in electrical parallel through an electrical powering system providing low voltage current. Each heated mat comprises relatively thin rectilinear laminated structure, having a rigid back panel with fastening means for positional maintenance, supporting a thin heating lamina having an element formed of electrically resistive metallic foil imbedded in plastic sheet material which in turn supports an outer surfacing lamina having an exposed surface of high friction material to prevent slipping. The laminae may carry plastic sheet material between adjacent surfaces and about peripheral edges to aid interconnection and isolation. All adjacent structural surfaces are mechanically joined. Each pad provides an electrical connector communicating spacedly from interconnection with its foil heating element. Each electrical connector is of the vampire type that may be releasably interconnected at selected positions along an elongate two-wire conductor to allow various modular arrays of plural heating mats about that conductor. The electrical system is powered by ordinary household current.
Japanese Patent No. 188,069 discloses a de-icing device for use with roof of building to remove snow therefrom. The device has temperature and weight sensors for controlling a power source supplying an RF current to several induction heating type coils.